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From: Tom Rini <trini@ti.com>
To: u-boot@lists.denx.de
Subject: [U-Boot] [RFC] Make i2c probe opt-outable?
Date: Fri, 18 May 2012 11:43:19 -0700	[thread overview]
Message-ID: <4FB69847.2090703@ti.com> (raw)
In-Reply-To: <20120518182659.6E492202A22@gemini.denx.de>

On 05/18/2012 11:26 AM, Wolfgang Denk wrote:
> Dear Tom Rini,
>
> In message<4FB674CD.8030502@ti.com>  you wrote:
>>
>>    But still, the kernel decided i2c probing is dangerous/unreliable,
>> maybe we should follow, or at least allow boards to follow?
>
> The kernel is in a very different situation - it is supposed to run on
> perfect hardware.
>
> In U-Boot, we have to dead with green hardware that is in a completely
> unknown state, or with hardware that _might_ be broken in one way or
> another.  For us tools doing low-level accesses are invaluable - even
> if they include the risk to hang a system.

Right.  I'm not suggesting removing i2c probe, I'm just suggesting 
making it opt-out'able.  For example, on the beaglebone I can make i2c 
probe work as expected.  It's just requring that we toggle the I2C_CON 
enable bit for some reason in probe, but not when we are actually trying 
to write to a bad address.  I'd like to just #undef CONFIG_CMD_I2C_PROBE 
for the board and be done with it.  Otherwise it lists (nearly) every 
address which is useless.

-- 
Tom

  reply	other threads:[~2012-05-18 18:43 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-05-17 18:43 [U-Boot] [RFC] Make i2c probe opt-outable? Tom Rini
2012-05-18  2:48 ` Mike Frysinger
2012-05-18 16:11   ` Tom Rini
2012-05-18 16:18     ` Mike Frysinger
2012-05-18 18:26     ` Wolfgang Denk
2012-05-18 18:43       ` Tom Rini [this message]
2012-05-18 21:52         ` Wolfgang Denk
2012-05-21 16:48           ` Tom Rini

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